Note: Descriptions are shown in the official language in which they were submitted.
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COMBINATION THERAPY FOR THE TREATMENT OF
ESTROGEN-SENSITIVE DISEASE
Cross-Reference to Related Applications
This application claims the benefit of priority under 35 U.S.C. ~ 119(e) to
application Serial
No. 60/238,772, .filed October 6, 2000, the contents of which are incorporated
herein by
reference.
Field of the Invention
This invention relates to a method of allowing or increasing the effectiveness
of
combination drug therapy for treating an estrogen-sensitive disease, such as
breast
cancer. The invention further relates to novel combination drug therapies and
methods for
treating an estrogen-sensitive disease.
Background of the Invention
U.S. Patent No. 5,550,107 to Fernand Labrie and others teach certain
combination drug
therapies for the treatment of estrogen-sensitive disease, e.g., breast and
endometrial
cancer. The patent teaches the combination of any of the listed antiestrogen
drugs with
any of the other listed drugs including androgen, a progestin, or an inhibitor
of sex steroid
formation, ACTH secretion, prolactin secretion, or growth hormone secretion.
One overarching problem with such otherwise unspecified combination treatments
for
breast cancer identified in the Labrie patent is the potential for one drug,
or class of drugs,
to cause an adverse effect on the absorption, distribution, excretion, or
metabolism (or
some combination of these) of one of the other drugs, or other classes of
drugs, employed
in the combination regimen. This problem is especially noteworthy in
postmenopausal
women who have primary or recurrent metastatic disease when surgery or
radiation
therapy may no longer be feasible and pharmaceutical therapy is the principal
remaining
treatment option. This kind of problem has been highlighted clinically in the
setting of
partially or completely failed attempts to combine an antiestrogen with an
inhibitor of sex
steroid hormone synthesis such as an aromatase inhibitor. Recent preclinical
and clinical
studies have shown that it is not possible to select an antiestrogen and pair
it with an
aromatase inhibitor to achieve the desired effect. Such unguided pairings lead
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treatment outcomes that are less than expected, with lesser antitumor effects
or
potentially even tumor stimulation, and that, as a result, may prove to be
harmful to the
patient.
It still remains desirable to control detrimental hormones (i.e., those
hormones which may
stimulate tumor growth) and to potentially block multiple pathways by which
these
hormones may be made in the body. However, prior art combination treatments
have
ignored the possibility that a drug that may, when used as monotherapy, block
one
hormone pathway may no longer do so as effectively, if at all, when another
(interfering)
drug is also present in the body. This unrecognized problem has the effect of
leaving
pathways wholly or partially available for formation of undesired tumor-
stimulating
hormones, thus diminishing or negating the desired beneficial effect of the
combination.
When considering antiestrogens as part of a combination regimen for treating
breast
cancer, prior art has emphasized the importance of selecting a "pure" estrogen
antagonist
having relatively little intrinsic estrogen agonist activity to the exclusion
of other potentially
important factors. If the purity of the antiestrogen activity were the only
factor that were
important in the selection of an antiestrogen as part of a combination
regimen, then
selection based on purity of activity would yield uniformly predictable and
beneficial clinical
results. This is demonstrably untrue. Even a pure antiestrogen, however, can
interact
adversely with other drugs. Similar deficiencies of reasoning have
characterized prior
recommendations regarding the selection of, for example, an inhibitor of sex
steroid
hormone synthesis such as an aromatase inhibitor. Prior art focuses on purity
and
selectivity to the relative exclusion of other essential factors in the
selection process,
namely, co-selection of the other drugs) in the regimen, and the potential for
adverse
effects of one drug on the absorption, distribution, metabolism, or excretion
of any other
drug in the regimen.
In the setting of the combination of an antiestrogen with an aromatase
inhibitor, for
example, prior art recommendations for establishing dosing regimens have
ignored the
potential that one drug in a combination may adversely influence the
absorption of a
second or third drug in the combination, leading either to low plasma levels
with
concomitantly reduced efFcacy or unexpectedly high plasma levels that increase
the risk of
toxicity. For example, the Labrie U.S. Patent 5,550,107 gives suggested dose
ranges for
the drugs to be combined, but says nothing about possible adverse
interactions, their
potential effect on the target dose ranges, how to achieve a target range in
the setting of
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one or more adverse interactions, and (most importantly) how to avoid such
adverse
interactions in the first place. See columns 22-24 of Labrie.
Prior art has also ignored the potential that one drug in a combination may
adversely
influence the distribution of a second or third drug in the combination.
Distributional
changes can occur because of changes in compartmentalization within the body,
changes
in transfer rates between compartments, changes in binding of one or more
drugs to
proteins that may serve as circulating ~~depots", or because of a combination
of these
factors. If the distribution is altered, then one or more drugs may not reach
the tumor in
adequate concentrations or intratumoral concentrations may be diminished. Such
effects
would reduce the efFcacy and potentially the safety of the combination. The
Labrie patent
does not address these important factors that may determine the utility and
safety of a
combination regimen.
Moreover, although prior art has, in general terms, warned of possible adverse
effects of
one drug on the metabolism of another, prior art has consistently failed to
provide
guidance on how best to avoid or to mitigate such interferences. Labrie also
fails to
provide teaching with respect to this adverse interaction. Such changes in
metabolism can
be the result of effects on one or more organs or tissues involved in disposal
of one of the
drugs in the pair.
Finally, in this setting of antiestrogen-aromatase inhibitor pairing, prior
art
recommendations regarding dosing regimens have fundamentally ignored the
potential for
drug-drug interactions on excretory pathways. Changes in excretion can also
lead to
changes in plasma or tissue levels that can adversely impact safety or
effectiveness or
both. Prior art has neglected the potential for multiple interactions
affecting
simultaneously two or more factors from absorption, distribution, excretion
and
metabolism. Finally, the extent of interference may change with timing of
dosing and the
passage of time, effects ignored by prior art, particularly in the setting of
combination
therapy involving an antiestrogen and an aromatase inhibitor.
In addition, prior art also has tended to emphasize the (sole) utility of
measuring plasma
levels of estrogens to assess effectiveness of treatment. However, plasma
levels of
estrogens are at best a surrogate for the level of estrogens present at the
estrogen
receptors) and plasma levels may be less than, substantially the same as, or
greater than
levels within a tumor itself. Moreover, endogenous estrogen levels may rise
with the use
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of an antiestrogen that blocks estrogen receptors (causing feedback
stimulation of
estrogen production) while estrogen levels may decline with the use of an
aromatase
inhibitor. When both classes of drugs are utilized together, the actual
interpretation of
plasma levels becomes uncertain. This difficulty in interpretation is made
significantly
greater when a regimen is utilized in which one drug interferes with the
activity of another,
and particularly when that interference changes with time. Moreover, the
sensitivity of a
tumor cell to an estrogen or an estrogen analogue can also change with time so
that
progressive falls in plasma levels of estrogens can still be associated with
marked tumor
stimulatory effects.
We have now discovered that combination drug treatment of estrogen-sensitive
diseases
can be made possible or significantly improved by considering the full
spectrum of
characteristics of each drug in the regimen before administering the
combination and not
just purity of activity or relative receptor selectivity. These
characteristics include: the
absorption, distribution, metabolism, and excretion of each drug in the
regimen and the
potential effect on the other drug (or drugs), and possibly certain
endocrinological effects.
The difficulties in interpreting only biochemical markers of "antiestrogen
therapy," such as
plasma markers, serve to emphasize the importance of properly choosing
regimens so that
unwanted changes in absorption, distribution, metabolism, and/or excretion are
minimized
or eliminated.
The deficiencies of the prior art necessarily diminish the effectiveness of
treatment,
increase the cost of effective treatment, increase the risk of toxic side
effects, and increase
the cost of treating such side effects.
Summary of the In vention
One aspect of this invention is a process for identifying a combination of
pharmacological
agents for the prevention or treatment of breast cancer in an animal,
preferably a human
female. The process comprises
identifying antiestrogen drugs and a therapeutically-effective dosage range
for an antiestrogen so identified;
determining the relevant aspects of absorption, distribution, metabolism,
and excretion (ADME) characteristics for the antiestrogen;
identifying sex steroid enzyme inhibitor drugs and therapeutically-effective
dosage ranges for an enzyme inhibitors so identified;
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determining the relevant aspects of ADME characteristics of an enzyme
inhibitor so identified;
choosing each drug and a dosage range for each drug such that each drug
exhibits useful therapeutic activity but each drug exhibits minimal
interference with ADME
of the other drug.
Another aspect of this invention is a method of treating breast cancer in
patient or
preventing breast cancer in an animal (preferably a human female) predisposed
to breast
cancer. The process comprises administering to the animal a therapeutically-
effective
amount of an antiestrogen drug and concurrently administering a
therapeutically-effective
amount of a sex steroid enzyme inhibitor drug, wherein the antiestrogen and
the enzyme
inhibitor, and dosage ranges for each, are chosen so that there is minimal
material
interference with the absorption, distribution, metabolism, and excretion
(ADME) of the
other drug.
1S Another aspect of this invention is a process for optimizing treatment of a
breast cancer
patient or for optimizing a cancer-preventive regimen for an animal
predisposed to such
cancer. The process comprises
identifying antiestrogens and a therapeutically-effective dosage range for the
antiestrogen so identified;
determining the relevant aspects of ADME characteristics for the antiestrogen
in the
patient;
identifying sex steroid enzyme inhibitors and a therapeutically-effective
dosage
range for an enzyme inhibitor so identified;
determining the relevant aspects of ADME characteristics for the enzyme
inhibitor
so identified;
selecting the antiestrogen and an enzyme inhibitor, and a dosage range for
each,
so that material interference by one drug on the other drug is minimized with
respect to
the ADME characteristics of one towards the other; and
co-administering the selected antiestrogen and enzyme inhibitor to the patient
at
the appropriate dosages.
Another aspect of this invention is a kit useful for treating breast cancer in
a patient
in need of treatment or for preventing breast cancer in a patient predisposed
to cancer.
The kit comprises an antiestrogen drug in a dosage form to provide a
therapeutically
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effective amount of the antiestrogen and a therapeutically effective amount of
an sex
steroid enzyme inhibitor drug, wherein the dosage form and amount of each drug
are
chosen so that material interference is minimized with respect to ADME
characteristics of
one drug towards the other drug.
Still another aspect of the invention is a pharmaceutical composition for
treating or
preventing breast cancer. The composition comprises a therapeutically-
effective amount
of an antiestrogen agent and a therapeutically-effective amount of a sex
steroid enzyme
inhibitor drug wherein the amount of each drug is chosen so that there is
minimal material
interference between one drug's ADME characteristics and the other drug's ADME
characteristics in a patient.
Other aspects will be apparent upon reading the detailed description of the
invention.
Brief description of the Figure
Figure 1 is a schematic diagram of some of the sites of action of the entities
that may play
a role in the production of steroids in a mammal.
Detailed Description and Presently Preferred Embodiment.
This invention is based in part on the discovery of how to identify certain
effective
combination regimens or how to maximize the effectiveness of other combination
regimens
for the treatment or prevention of cancer, particularly breast cancer, via
avoiding or
minimizing certain drug-drug interactions. In the past it has been broadly
taught that
breast and endometrial cancer can be treated by administering any antiestrogen
and any
other hormonal agent, such as an androgenic agent, a progestin, or inhibitor
of an enzyme
that catalyzes a step in the synthesis a sex steroids from their precursors in
peripheral
tissues through a non-adrenal mechanism (see U.S. Patent No. 5,550,107 to
Labrie).
Other agents also can be used. Random combinations are unlikely to yield
useful regimens
for the reasons stated in the ~~Background of the Invention," and,
accordingly, the
development of combinations and dosages that are therapeutically effective has
proven
elusive. We believe that the prevention or treatment of a breast cancer in a
patient, either
male or female, can be made possible or optimized by taking into account
certain
interactions between the antiestrogen and the inhibitor (and other agents)
that are part of
the combination.
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"Treatment" of breast cancer means the administration of the combination
therapy of this
invention to reduce the presence of the cancer (e.g., reduce tumor size), to
prevent the
expansion of the cancer (e.g., prevent the cancer from spreading), or to
stabilize the
cancer.
"Prevention" of breast cancer means the administration of the combination
therapy of this
invention to prevent the onset or recurrence of a cancerous condition in a
subject
predisposed to, or at risk of, the condition.
One aspect of the invention can be viewed as a process for identifying a
combination
treatment of breast cancer in a warm-blooded animal. While the invention is
useful in any
warm-blooded animal that may develop breast cancer, it is most useful for
human female
patients, as the vast majority of cases treated are in human females. The
process
comprises identifying a antiestrogen and a therapeutically-effective dosage
range for the
antiestrogen, i.e., a dosage range showing anticancer activity. The relevant
aspects of
absorption, distribution, metabolism, and excretion characteristics of the
antiestrogen in
the patient are determined. At least one other agent having tumor-inhibiting
activity, i.e.,
an inhibitor of sex steroid biosynthesis, is identified along with a dosage
range for the
other agent. The degree of interference of each agent with the other agent's
absorption,
distribution, metabolism, and excretion is determined, and the dosage of the
two agents
chosen for combination is adjusted to maximize the therapeutically-effective
anti-tumor
activity of the two agents while minimizing material interference on the
absorption,
distribution, metabolism, or excretion function of the agents. Preferably, the
antiestrogen
and the other agent are chosen so that there is no material interference with
the
absorption, distribution, metabolism, and excretion (ADME) for either agent.
The
combination may also include an androgen, a progestin, a glucocorticoid, or an
inhibitor of
growth hormone secretion, prolactin secretion, or ACTH secretion, also chosen
so that
there is minimal material interference with the ADME characteristics.
In conjunction with teaching of how to make and use the invention, it is
useful to discuss
the presently understood background behind breast cancer treatment using tumor-
inhibitory compounds, i.e., compounds showing anticancer activity.
Many breast cancer tumors are estrogen dependent, i.e., the growth of the
tumor is aided
by the presence of estrogen, which activates a receptor that sends a signal
for the tumor
cells to multiply. In the presence of an antiestrogen, a tumor will not grow
as fast, may
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not grow at all or may shrink in size. An antiestrogen is a substance capable
of preventing
full expression of the biological effects of estrogenic hormones on responsive
tissues e.g.,
by competing with estrogens at estrogen receptors at the cellular level and
blocking the
receptor. Such an "antiestrogen" is a compound that blocks an estrogen
receptor in the
target cell and can be referred to as an estrogen receptor blocker or ERl3.
However,
estrogen may still be manufactured in the patient's tissues and some of that
estrogen may
find receptors and still send a growth signal. Thus, the idea of using another
tumor-
inhibitory agent, e.g., an inhibitor of an enzyme that catalyzes the
production of a sex
steroid that could ~t into an estrogen receptor, arises (e.g., see U.S.
5,550,107). As
mentioned previously, the problem we have identified is that the antiestrogen
and the
other agent will or can interfere with the other's absorption, distribution,
metabolism and
excretion characteristics and thus the effectiveness of the individual agents
in combination
is adversely affected. Our solution to the problem gives a Non-interfering
Combination
that retains Effectiveness, abbreviated as a "NCE" composition.
Figure 1 is a schematic diagram of some of the sites of action of the entities
that may play
a role in the production of steroids in a mammal.
The following abbreviations are used in Figure 1:
ER: estrogen receptor
AR: androgen receptor
PR: progesterone receptor
GR: glucocorticoid receptor
DHEAS: dehydroepiandrosterone sulfate
DHEA: dehydroepiandrosterone
DELTA.5-diol: androst-5-ene-3f3,17f3-diol
DELTA.4-dione: androstenedione
E : estrogen
E1: estrone
E2 : 17f3-estradiol
T: testosterone
DHT: dihydrotestosterone
E2 S: E2 -sulfate
E1 S E1 sulfate
(1) LHRH-A luteinizing hormone-releasing hormone agonist or antagonist;
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(2) ANTI-E: antiestrogen
(3) AND: androgen
(4) PROG: progestin
(5) l7fi-HSD inhibitor of 17f3-estradiol steroid dehydrogenase
or
17f3-hydroxysteroid dehydrogenase
(6) ARO: inhibitor of aromatase activity
(7) 3f3-HSD: inhibitor of 3fi-hydroxysteroid, .DELTA.5
-.DELTA.4 isomerase;
(8) INH: inhibitor of adrenal steroidogenesis
(9) IPRL: inhibitor of prolactin secretion
(10) IGH: inhibitor of growth hormone secretion
(11) IACTH: inhibitor of ACTH secretion
(12) NCE: Non-Interfering Combination that retains
Effectiveness
(13) LTED: Long term estrogen deprivation
Referring to FIG. 1, the "+"s and "-"s next to each indicated receptor
designate whether
activation of that receptor aids or hinders tumor growth. As may be seen from
FIG. 1,
activation of the estrogen receptor will stimulate tumor growth and is
therefore to be
prevented. However, it is important to continue to activate other receptors,
whose
activation may inhibit tumor growth, e.g., the androgen receptor, the
progesterone
receptor, and the glucocorticoid receptor.
Estrogen may be produced by a number of pathways, all of which can be affected
by the
pituitary. (1) luteinizing hormone (LH) stimulates the ovaries to release E2,
which is then
metabolized to estrogen with the aid of aromatase; (2) LH stimulates the
ovaries to release
DELTA 4-dione, which is then metabolized to E1 and on to estrogen; (3)
andrenocorticotropic hormone (ACTH) is secreted to stimulate the adrenal
glands to
produce DHEAS, which can be metabolized to estrogen; (4) proiactin secretion
may
stimulate the adrenals to produce DHEAS and on to estrogen. As can be seen,
there are
various routes to block the production of estrogen to minimize the amount
available for the
estrogen receptor.
One method of inhibiting activation of the estrogen receptor is treatment with
an effective
and properly selected antiestrogen compound, suitable for inclusion in an NCE
regimen,
and having an afFnity for the receptor site such that it binds the receptor
site and blocks
estrogen from binding and activating the site. It can be useful to select
antiestrogens
which tend to be pure antagonists, and which have no agonistic activity, but
only if the
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selection retains the benefits of establishing an NCE regimen. Otherwise, the
purity and
relative absence of estrogen agonistic activity may be overcome by other
factors such as
changes in ADME characteristics or endocrine characteristics, of one or more
concurrently
administered drugs, as discussed hereinafter. Examples of antiestrogens are
discussed in
detail hereinafter.
Because it is extremely difficult to block all receptor sites, it is desirable
to simultaneously
decrease the concentration of estrogen available to activate estrogen
receptors, i.e., to
reduce the ovarian hormonal secretions. Hence, it is desirable to inhibit
production of
estrogen by the ovaries. In postmenopausal women, ovarian function has
effectively
ceased and no antiovarian therapy is generally required as such. However, in
pre-
menopausal women, it may be useful to suppress ovarian function either by
chemical or
surgical means. Chemically this can be accomplished by administering an
appropriate
luteinizing hormone releasing hormone ('~LHRH" also referred to as GnRH or
gonad
releasing hormone) agonist or antagonist, such as those discussed hereinafter.
Surgically,
this can be accomplished by removing the ovaries through an oophorectomy. All
aspects
of this invention are particularly useful in postmenopausal women.
As may be seen from the scheme of FIG. 1, a number of sex hormones precursors
released
by the adrenals may be converted by a variety of non-adrenal biological
pathways into
estrogen in the peripheral tissues. Among the hormone precursors thus produced
are 17f3-
estradiol and androst-5-ene-3f3,17f3-diol. It is therefore highly desirable to
include an
inhibitor of an enzyme that catalyzes a step in the synthesis of a sex steroid
from such
precursors. Such enzymes include, for example 17f3-estradiol dehydrogenase or
17f3-
hydroxy steroid dehydrogenase. Such an inhibitor will close down the synthetic
pathways
crossed by vertical line 5 denoted "17f3-HSD" on FIG. 1. Hence synthesis of
both major
forms of estrogen shown on FIG. 1 is substantially prevented. Other sex
steroid formation
inhibitors such as inhibitors of 3f3-hydroxy steroid or of aromatase activity
are also
preferably included in treatment in order to close down the synthetic pathways
crossed by
the two horizontal lines 6 and 7 denoted "ARO" and "3fi-HSD", respectively.
Aromatase is
an enzyme that aids in aromatizing the A ring in the basic steroid structure.
It will be noted from Figure 1 that the use of an aromatase inhibitor has the
effect of
reducing estrogen levels while potentially maintaining or even increasing
androgen levels
(androgen precursors are not converted into corresponding estrogens and
therefore
remain "available" as androgens). In contrast to the situation in which
androgen secretion
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is also inhibited, use of an aromatase inhibitor (in addition to an
antiestrogen) has the
added benefit of potentially simplifying the regimen because there is no need
to administer
exogenous androgens. By choosing the combination of an antiestrogen with an
appropriate enzyme inhibitor to minimize the adverse ADME interactions, an
optimum
composition can be obtained.
In summary then, the process for identifying a combination treatment of breast
cancer in
an animal comprises
identifying antiestrogen drugs and a therapeutically-effective dosage range
for an antiestrogen so identified;
determining the relevant aspects of absorption, distribution, metabolism,
and excretion characteristics of the antiestrogen for the animal;
identifying sex steroid enzyme inhibitor drug; and a therapeutically-effective
dosage range for an enzyme inhibitor so identified;
determining the relevant aspects of absorption, distribution, metabolism,
and excretion characteristics of an enzyme inhibitor so identified in the
animal;
choosing each drug and a dosage range for each drug such that each drug
exhibits useful therapeutic activity but exhibits minimal interference with
the absorption,
distribution, metabolism, and excretion of the other drug.
With our discovery of the manner of identifying a combination treatment of
breast cancer,
another aspect of the invention can be seen. This aspect of the invention is a
method of
treating breast cancer. The method is particularly useful in female patients
with reduced
hormonal secretions, e.g., postmenopausal women, women who have had their
ovaries
removed surgically, or women who have had their ovarian function suppressed by
chemical
means. The method comprises administering a therapeutically-effective amount
of an
antiestrogen agent and concurrently administering a therapeutically-effective
amount of at
least one other agent having tumor inhibitory activity, the agents and dosage
ranges being
chosen so that there is minimal material interference of one agent's ADME
characteristics
by the other agent. Preferably the other agent is a sex steroid enzyme
inhibiting agent.
Specifically, the other agent is an aromatase inhibiting agent.
Once the combination of these first two agents is determined, other agents can
be
included using the ADME analysis as described herein.
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The other agents that can be included in the method of treatment include an
androgen, a
progestin or a glucocorticoid to fit into the appropriate receptor to aid the
inhibition of the
growth of the cancer. Other agents are inhibitors of growth hormone secretion,
inhibitors
of prolactin secretion, and inhibitors of adrenal corticotrophin hormone
(ACTH) secretion.
The latter has the effect of preventing ACTH from reaching the adrenals and
thus of
preventing the adrenals from synthesizing and secreting compounds such as
DHEAS, a
precursor in the synthesis of estrogen. Alternatively, inhibitors that close
down synthetic
pathways in the adrenals will achieve the same result. When adrenal secretions
are
inhibited or stopped, essential glucocorticoids should be added back as part
of the therapy.
However, all such additions much consider the requirements to effect, in
aggregate, a NCE
regimen, i.e., an optimized combination which minimizes the adverse
interactions among
the entities' ADME characteristics. The method of optimizing treatment or of
treating
breast cancer employs at least two agents and may include more.
In another aspect of the invention, i.e., the treatment of breast cancer in a
human female
whose ovarian function has been interrupted (naturally via menopause, by
surgery or by
other means), the method comprises administering to the woman a
therapeutically
effective amount of a properly selected antiestrogen and a properly selected
other agent
(e.g., one that inhibits an enzyme catalyzing sex steroid formation, such as
an aromatase
inhibitor) to provide an NCE regimen. In addition to the example given of an
antiestrogen
and the enzyme inhibitor in the treatment, at least one additional compound
may be
added, which includes an androgen, a progestin, a glucocorticoid, an inhibitor
of prolactin
secretion, an inhibitor of growth hormone, or an inhibitor of ACTH secretion.
Mixtures of
such compound are also useful.
In selecting candidate drugs in an NCE Regimen and determining how to judge
the levels
of components in the treatment regimen, one determines the effect of one
component on
the other's ADME, and optionally endocrine, profile. Candidates are evaluated
and selected
according to the hierarchy shown in Table I, with the fewer number and level
of
interferences being preferred.
The object of the evaluation of the effect of each drug on the ADME
characteristics and
optionally endocrine profile of the other is to avoid material interference
between the two
drugs. Material interference means that one drug is interfering with the ADME
characteristics, or endocrine function sufficiently to measurably reduce the
efficacy of the
other drug and/or measurably increase the toxicity of the other drug. One can
avoid
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material interference by following the analysis set forth in the ensuing
discussion. The
analysis includes the endocrine profile as parts of the analysis. This is
preferred but not
absolutely required. Moreover, it may also be desirable to consider
similarities or
dissimilarities in chemical structures of molecules to be combined within a
regimen and
underlying pharmacokinetic parameters (including but not limited to times to
maximal
plasma level, absorption/distribution/elimination half lives, route and extent
of organ
clearance, overall time to steady-state). The relevant aspects of absorption
include factors
such as the route of absorption (e.g. oral), the influence of timing, and the
amount and
type of food or caloric intake that might affect plasma levels. Relevant
aspects of
distribution include, i.a., the extent and characterization of plasma protein
binding, while
relevant aspects of excretion include the primary routes) of elimination and
the presence
or absence of enterophepatic circulation. The relevant aspects of metabolism
include the
primary enzymes involved in metabolism or clearance, whether metabolizing
enzymes for
one drug are induced by another, and at what dose levels, the effect of other
enzyme
inducers, whether a metabolite is active and at what relative level, and the
presence of
significant pre-systemic metabolism. The relevant aspects of the endocrine
effect includes
the primary endocrine mechanism, whether feedback stimulation or inhibition
occurs, and
whether direction inhibition of a primary endocrine mechanism is operative.
Other
considerations include organ (eg. liver or kidney) dysfunction influences on
ADME
parameters, demographic factors (e.g. as race, sex, age), genomic factors such
as single
nucleotide polymorphisms or haplotypes or allelic or chromosomal profiling.
Others may
be apparent to one of skill in the art.
As shown in Table II, there are five categories of possible interference,
including
interference with absorption, distribution, metabolism, excretion, or with
endocrine
function. InterFerences may occur singly or in combination. It will be clear
to those skilled
in the arts that the following represent the number of possible combinations
of
interFerences:
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Table I
Number of Different Combinations of Interferences
Number of Number of
Categories Different
with Combinations
Interferences
0 1
1 5
2 10
3 10
4 5
_ _ 5 - _ I -1
In Table II are shown more detailed descriptions of the possible categories of
interFerences. In Table II, a drug is considered with respect to one other
candidate drug in
the regimen. This is a ~~first-order" ranking process. Smaller ranking numbers
are, in
general, preferable to larger ranking numbers because a smaller number
indicate a smaller
number of categories of interference without necessarily quantitating,
however, the degree
of interference for any one category.
14
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Table II
Combinations of Interferences
Number InterferenceInterferenceInterferenceInterferenceInterference
of ~e~er with Relativ
with with with with
PositiveIdentifierAbsorptionDistributionMetabolismExcretionEndocrinea
Categorie Effect Ranlein
s g
0 A no no no no no 1
~:' A yes ' no,. no n no . 2
no yes no no no 2
1 C no no yes, no no 2
1 . - D no no no yes . no;:' ~ 2
E no no no n~: ~ yes,P,
2 A yes yes no no no 3
2 B yes no yes no no 3
2 C yes no no yes no 3
2 D yes no no no yes 3
2 E no yes yes no no 3
2 F no yes no yes no 3
2 G no yes no no yes 3
2 H no no yes yes no 3
2 I no no yes no yes 3
2 J no no no yes yes 3
3 TA ,.no no yes ' yes Yes
3 B ,. rio yes . Yes., eyes .
no
3 . C ,~ no yes Yes no
yes ; q.
J D do Yes Yes yes ' no
E Yes ono no yes . yes W 4 .
'
3 F yes mo Yes no yes .' q,
'
.
3 . G yes no ;yes yes no ''
3 H dies yes no no . yes 4
J - ;I ,yes yes no , t Yes' n~
- ?
3 : ,J yes yes ' Yes ' no . no'
4 A yes yes yes yes no 5
4 B yes yes yes no yes 5
4 C yes yes no . yes yes 5
4 D yes yes yes no yes 5
4 E yes yes yes yes no 5
A yes yes yes -yes yes 6
The characteristics of the relative ranking of 1 are preferred for a single
drug considered as
5 part of a combination: There is no interference with important
characteristics of other
drugs. Accordingly, this is a good candidate molecule for an NCE regimen
member. For a
drug with a ranking of 6, with interferences in all categories, the drug would
not be a good
candidate molecule for an NCE regimen member,
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The ranking process is repeated for each candidate drug. For two different
drugs with the
same first-order relative ranking (2, 3, 4 or 5) a second-order ranking
process may be
necessary.
For example, consider the five possibilities in Table III in which the number
of positive
categories is equal to 1 (each of the categories is also labeled with a
letter, A-E, for clarity
in comparisons within this category).
Table III
Example: One Positive Interference Category
Number InterferencInterferencInterferencInterferencInterferenc
of
Positive a with a with a with a with a with Relative
CategoriesAbsorptionDistributionMetabolismExcretionEndocrine Ranking
Effect
'. , ~,A yes no no no. ~ no ~ 2 .
. .
l-B no yes no no no
1-C ' , no ' no dyes no no 2 ,,,
; =
1-f~ nc~ T no ono 'yes r no ~2 ,'
ri no . 'Pno ,. no , .~ , 2-
o yes ;,
In each case there is an interference with one of the five categories.
Interaction in the
category 1-A may lead to reduced anti-tumor activity, which may not fully be
correctable,
even by giving higher doses of the drug in question because one drug is not
absorbed due
to the material interference by the other drug. Category 1-B can be associated
with lower
or higher bioavailability (due to improper distribution in the body) and,
therefore, a higher
or lower cost, respectively, to achieve a pharmaceutical effect. Whether lower
or higher
must be determined or estimated with reasonable accuracy. Category 1-B,
interference
with distribution, is best judged by plasma or tissue levels of active drug
[or the active
metabolite(s)] of the active drug. In category 1-C, if metabolism is
accelerated, then 1-C
is similar to 1-A (less parent drug is available), while if metabolism is
retarded then 1-C is
more similar to 1-D as described below. If the metabolite is the active
moiety, however,
then accelerated metabolism can also produce results more similar to those
described in 1-
D. Category 1-D is typically associated with higher bioavailability (i.e.,
less drug is
excreted so more stays in the system) and, therefore, potentially it may be
possible to
administer less drug to obtain the same effect. Category 1-E, interference
with an
endocrine effect may be similar to 1-A, 1-B, or 1-C, where, for 1-C metabolism
of the
active moiety is accelerated.
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In general, the goal will be to select the drug in the category that is
associated with the
administration of the smallest (and therefore most cost-effective) amount of
drug to
achieve a given therapeutic effect. An effect in a category does not always
indicate the
magnitude of the effect within that category, and quantitation is desirable
where possible.
Table IV
Example: Two Positive Interference Categories
Number InterferenceInterferenceInterferenceInterferenceInterference
of with with with with with Relative
PositiveAbsorption DistributionMetabolism Excretion Endocrine Ranking
Categorie Effect
s
2-A yes yes no no no 3
2-B yes No yes no no 3
2-C yes No no yes no 3
2-D yes No no no yes 3
2-E no yes yes no no 3
2-F no yes no yes no 3
2-G no yes no no yes 3
2-H no no yes yes no 3
2-I no no yes no yes 3
2-.7 no - I no ~ no _ ~ yes- ~ _ yes
I
Where two categories are affected by one drug, the analysis becomes more
complex. In
these scenarios, the interfering effects can be additive, synergistic, or
antagonistic. For
example, in 2-A, diminished absorption and diminished distribution can be
adversely
additive or synergistic (i.e., much less drug reaches the target sites).
However, it is
possible that a change in distribution can counterbalance a reduction in
absorption. In 2-B
and 2-C, diminished absorption may also possibly be countered by the
interference with
metabolism or excretion. In 2-D, the effects will most probably be adversely
additive or
synergistic (lower absorption and less endocrine effects will "add" to
diminish the beneficial
effect). In 2-E and 2-F, the effects may counteract one another although a
change in
distribution can add to the interference with metabolism under certain
circumstances. In
2-G, the interference may be counteractive or may be additive or synergistic
to diminish a
drug effect, while in 2-H an additive or synergistic effect may actually
enhance a drug
effect. In 2-I and 2-J, effects may counteract one another. The complexity
emphasizes
the essential nature of the current invention to best choose drug
combinations.
If each category from the Table II labeled "Combination of Interferences" is
shown by
number and letter, then each combination of interferences may be assigned a
probable
17
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qualitative overall interaction value where the combination of interFerences
has an overall
increase in or positive (POS) effect or an overall reduction in or negative
(NEG) effect on
the pharmacological activity of the drug that is the subject of the
interaction. As noted,
however, changes in pharmacological activity may also be accompanied by
changes in
toxicological activity. It is also possible that one interference may
counteract, i.e.
antagonize (ANT) the effect of another interference so that an overall POS
effect or NEG
effect becomes more difficult to predict without extensive and quantitative
ADME data for
both agents, singly and in combination. See Table V.
Table V
Probable Effect of Combinations of Interactions on a Target Drug
Designation Probable Effect
of of Combination
Categories of Inferences
0-A NONE
1-A NEG
1-B POS/NEG
1-C POS/NEG
1-D POS
1-E NEG
2-A ANT/NEG
2-B ANT/NEG
2-C ANT
2-D NEG
2-E POS/ANT/NEG
2-F POS/ANT
2-G ANT/NEG
2-H POS/ANT
2-I ANT/NEG
2-J ANT
3-A ANT
3-B ANT
3-C ANT
3-D ANT
3-E ANT
3-F ANT/NEG
3-G ANT
3-H NEG/ANT
3-I ANT
3-7 ANT/NEG
4-A ANT
4-B ANT
4-C ANT
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4-D ANT
4-E ANT
5-A ANT
While the positive, negative, or antagonistic interactions described in the
table above are
qualitatively accurate, it is possible that one interference may so dominate
the overall
biological effects that the potential antagonism may be difficult to ascertain
solely on a
qualitative basis. As indicated, it is also possible that the overall
interference effect of a
category 1 or category 2 drug may be greater than the interference effect of a
category 3,
4, or 5 drug, even though the latter categories have a larger "number" of
interferences. In
this instance, it is the net magnitude and direction of interference rather
than the number
of interferences that is more important. The complexity of these interactions,
and the
number of potentially interacting factors, serves further to underscore the
deficiencies in
prior art in the area of combination therapy in breast cancer.
When one drug has been subjected to such one or more drug-drug analyses as
described
above, then the next drug to be considered for an NCE regimen can be similarly
analyzed.
Then the relative benefits of one drug, considered in the framework of this
NCE-regimen
analysis, can be compared to those of the second drug, also having been
considered in the
same analytical framework. Relative risk assessments, relative efficacy
assessments, and
relative cost-of goods assessment can be then performed and the most
appropriate drug
combinations) selected.
The ADME ahd endocrine interferences between any two drugs can be determined
by
researching the information from literature or from database sources or by
empirical
means, i.e., from in vitro or in vivo experimentation.
Tools to consider employing to determine ADME interferences include
pharmacokinetic
and/or pharmacodynamic analyses in animals or in humans with standard single-
or multi-
compartment pharmacokinetic analyses of blood, plasma, tissue, or tumor
levels. In vivo
methods are explained in standard texts.
However, those skilled in the arts will recognize that plasma levels of
estrogens (and
sometimes plasma levels of drug(s)) are only surrogates for a final assessment
of relative
effectiveness and relative safety.
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Once the qualitative and/or quantitative data are gathered for the combination
of interest,
the dosages are adjusted to eliminate or minimize the interFerence of one
agent by
another.
A practical example to demonstrate the application of the NCE algorithm may be
seen in
the concept of combining an anti-estrogen and an aromatase inhibitor for the
first line
therapy of advanced postmenopausal breast cancer. Since these patients are
already
postmenopausal, i.e., they have reduced ovarian hormonal secretions, a
combination with
an LH-RH agonist would not be seen as adding benefit to this combination. A
recent
publication by Santen et al (Yue W, Berstein L, Wang J P, Santen R J, Long
term estrogen
deprivation (LTED) enhances aromatase activity in breast cancer cells.
Proceedings, 91st
Annual Meeting of the American Association for Cancer Research, Volume 41,
Abstract
2376, 2000) using an in vitro model of cultured estrogen-sensitive MCF-7
breast cancer
cells in estrogen-deprived medium, demonstrated these cells to initially stop
growing, but
to consequently show comparable growth rate as in estrogen-containing medium.
This
model mimics growth inhibition by antiestrogens used clinically and suggests
that
estrogen-deprived cells remain responsive to estrogen but may require much
lower
amounts of estrogen for proliferation. Since the authors found aromatase
activities in LTED
cells to be 3-4 fold higher than in wild type MCF-7 cells, they conclude that
LTED
upregulates aromatase. Enhanced aromatase activity may be thus be partially
responsible
for the adaptation of breast cancer cells to low estrogen environment.
Consequently, the proposed combination of an antiestrogen blocking the
estrogen receptor
function and an aromatase inhibitor reducing the activity of tumoral aromatase
is
supported preclinically. Attempting to identify a most suitable combination of
drugs, one
would soon realize that there are currently two antiestrogens clinically
available, tamoxifen
and toremifene, as well as four aromatase inhibitors, including letrozole.
Other
representatives of each drug class are in clinical testing. Considering
combinations of
these compounds helps to exemplify the NCE regimen approach.
An agonistic effect of tamoxifen on the uterus was observed when it was given
alone and
when combined with an aromatase inhibitor, which indicates that the residual
agonistic
estrogenic signal caused by tamoxifen is both measurable and relevant and is
not
controlled by addition of aromatase inhibitors: (Brodie A, Lu Q, Liu Y, Long
B, Wang JP,
Yue W. Preciinical studies using the intratumoral aromatase model for
postmenopausal
breast cancer. Oncology (Hunting); 12(3 Suppl 5):36-40, 1998) If the
antiestrogen in
CA 02424299 2003-03-28
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question were to be toremifene, the residual agnostic estrogenic signal at
doses used
clinically would be up to 40-fold less than that of tamoxifen as shown by Di
Salle et al (Di
Salle E, Zaccheo T, Ornati G, et al. Antiestrogenic and antitumor properties
of the new
triphenethylene derivative toremifene in the rat. Journal of Steroid
Biochemistry. 36: 203-
206, 1990).
Tamoxifen and letrozole represent one potential combination of an antiestrogen
and
aromatase inhibitor. However, it has been shown and published that estrogen
suppression
was not enhanced by this combination and, as a result, the antitumor effect of
tamoxifen
plus letrozole was less than expected. (Ingle JN, Suman VJ, Johnson PA, Krook
JE,
Mailliard JA, Wheeler RH, Loprinzi CL, Perez EA, Jordan VC, Dowsett M.
Evaluation of
tamoxifen plus letrozole with assessment of pharmacokinetic interaction in
postmenopausal
women with metastatic breast cancer. Clin Cancer Res. Jul;S(7):1642-9, 1999).
In addition, during combination therapy with tamoxifen, plasma levels of
letrozole could be
reduced by a mean of 37% as compared to single agent treatment with letrozole
alone,
and this reduction persisted during months of combination therapy. (Dowsett M,
Pfister C,
Johnston SR et al. Impact of tamoxifen on the pharmacokinetics and endocrine
effects of
the aromatase inhibitor letrozole in postmenopausal women with breast cancer.
Clin
Cancer Res; 5(9):2338-43, 1999) Tamoxifen and letrozole share multiple
cytochrome p450
isoenzymes, which have been shown to be induced by tamoxifen (Nuwaysir E,
Dragan YP,
Jefcoate CR, et al. Effects of tamoxifen administration on the expression of
xenobiotic
metabolizing enzymes in the rat liver. Cancer Res; 55:1780-89, 1995).
Combination
therapy with tamoxifen can lead to increased metabolism. This combination
would be
adverse due to interference with metabolism. It is possible that this
unexpected interaction
of tamoxifen with another drug might affect the efficacy of other anticancer
agents.
The above examples also make clear that information regarding possible
interference does
not necessarily have to rely on newly generated preclinical or clinical data,
but may well be
readily available from published references. It is necessary to utilize the
methods
described in the current invention, however, in order to make optimal use of
such data. As
part of the NCE approach a deliberate effort is made to collect, review and
apply the
available data for the improving treatment of patients with breast cancer.
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In selecting component drugs for a NCE regimen it is also useful to consider
and to
balance the following characteristics of each drug being considered for
inclusion: protein
binding and the concentration or amount of excipients and activity, if any, of
excipients.
In choosing the active agents useful in the various aspects of this invention,
one should
consider specific agents in the categories set forth hereinafter.
Antiestrogens
The antiestrogen compounds useful in the various aspects of this invention
include many
compounds that are well known in the art. Two preferred compounds are
tamoxifen and
toremifene, along with the pharmaceutically acceptable salts of these
compound.
Presently these compounds are commercially available as Novaldex~ from Astra
Zeneca
Pharmaceuticals and Fareston~ from Shire Pharmaceuticals.
Tamoxifen's chemical name is (Z)-2-[4-(1,2-diphenyl-1-butenyl)-phenoxyl]-N,N-
dimethylethanamine or 1-p-~i-dimethylaminoethoxyphenyl-trans-1,2-diphenylbut-1-
ene. Its
chemical formula is
Toremifene's chemical name is (Z)-2-[4-(4-chloro-1,2-diphenyl-1-
butenyl)phenoxy]-N,N-
dimethylethanamine. Its chemical formula is
a
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Others are set forth in U.S. Patent No. 5,550,107 to Labrie, which is
incorporated herein by
reference. Typical suitable antiestrogens include those steroidal and non-
steroidal
antiestrogens such as (1RS,2RS)-4,4'-diacetoxy-5,5'-difluoro-(1-ethyl-2-
methylene)di-m-
phenylenediacetate, which is available from Biorex under the trade name of
Acefluranol;
6.alpha.-chloro-l6.alpha.-methyl-pregn-4-ene-3,20-dione which is available
from Eli Lilly &
Co., Indianapolis, Ind, under the trade name of Clometherone; 6-chloro-17-
hydroxypregna-1,4,6-triene-3,20-dione which is available as the acetate salt
as Delmadione
Acetate; 17-hydroxy-6-methyl-19-norpregna-4,6-diene-3,20-dione which is
available from
Theramex under the name of Lutenyl; 1-[2-[4-[1-(4-methoxyphenyl)-2-nitro-2-
phenylethenyl)phenoxy]ethyl]-pyrrolidine which is available as the citrate
salt from Parke-
Davis Div. of Warner-Lambert Co., Morris Plains, N.J. under the name of
Nitromifene
Citrate; substituted aminoalkoxyphenylalkenes such as tamoxifen citrate salt
from Stuart
Pharmaceuticals, Wilmington, Del. (see also Belgian patent No. 637,389, Mar.
1964); 3,4-
dihydro-2-(p-methoxyphenyl)-i-naphthyl p-[2-(1-pyrrolidinyl)ethoxy]phenyl
ketone which
is available as the methane sulfonate salt from Eli Lilly & Co. under the
tradename of
Trioxifene Mesylate; 1-[4'-(2-phenyl)-bl-(3'-hydroxyphenyl)-2-phenyl-but-1-ene
which is
available from Klinge Pharma; [6-hydroxy-2-(p-hydroxyphenyl)-benzo(b)thien-
3yl]-[2-(1-
pyrrolidinyl)-ethoxy phenyl]ketone which is available from Eli Lilly & Co. (LY
117018); [6-
hydroxy-2-(4-hydroxyphenyl)benzo(b)thien-3-yl]-[4-(2-(1-
piperdinyl)ethoxy)phenyl]methanone, which is available from Eli Lilly & Co. as
the
hydrogen chloride salt (LY156758); meso-3,4-bis(3'-hydroxyphenyl) hexane as
well as the
dimethyl, dipropyl and 3'-acetoxy phenyl analogues which are described in U.S.
Pat. No.
4,094,994; and a series of 1-phenyl-alkane and -alkenes, e.g.,(E)-3-
cyclopentyl-1-(4-
hydroxyphenyl)-1-phenyl-1-butene and 2-cyclo-pentyl-1-[4-hydroxy or
methoxyphenyl]-3-
phenyl-2-propen-1-of and FC-1157 which are available as the citrate salt from
Farmos
Group, Ltd., Turku, Finland (see also Eur. Pat. Appln. Ep. No 78,158). It is
preferred to use
an antiestrogen which shows minimal partial estrogen agonism. Toremifene and
tamoxifen
are at the preferred antiestrogens of the class of those possessing some
agonistic activity.
Other suitable antiestrogens also include 7.alpha.-substituents of estradiol
(European Pat.
No. 0138504) and non-steroidal compounds bearing a similar aliphatic side-
chain (U.S. Pat.
No. 4,732,912), both of which are incorporated herein by reference.
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Other suitable antiestrogens may be found by accessing PHARMAPROJECTS data
base.
For example PHARMAPROJECTS accession number (PAN) 28929 refers to antiestrogen
being developed by Schering Plough.
Other compounds include the following:
PAN 24611: The chemical name is
4-methyl-2[4-[2-(1-piperidinyl)ethoxy]phenyl]-7-(pivaloyloxy)-3-[4-
(pivaloyloxy)phenyl]-
2H-1-benzopyran (code name EM-800). The chemical formula is
II
0
0
0
~N
PAN28952: SH-646 being developed by Schering AG.
PAN18136: Lasofoxifene was originated by Ligand. The chemical name is 5,6,7,8-
tetrahydro-6-phenyl-5-(4-(2-(1-pyrrolidinyl)ethoxy)phenyl-(5R-cis)-2-
naphthalenol, (S-(R*,
R*))-2,3-dihydroxybutanedioate. The chemical formula is
HO
0
0
"~~' HO "~ .
QH
QH
HO
/ ~'w,
PAN25625: 2-methoxyestradiol is being developed by EntreMed. The chemical
formula is
24
CA 02424299 2003-03-28
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nu
~,,,.0
HO
PAN25983: LY-326391 was originated at Eli Lilly. The chemical name is 2-(4-
methoxyphenyl)-3-(4-(2-(1-piperidinyl)ethoxy)phenoxy)-benzo(b)thiophene-6-ol,
hydrochloride. The chemical structure is
0 ~
..~'~ H -GI
PAN13172: A-007 was originated by Dekk-Tec. The chemical name is 4,4'-
dyhydroxybenzophenone-2, 4-dinitrophenylhydrazone. The chemical structure is
O~hl#0_
~ ~H~ ~
H
Nr
H 0 ~'' ~'' 0 H
PAN28528: ERA 923 was originated by American Home Products and licensed to
Ligand.
CA 02424299 2003-03-28
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PAN15322: Fluvestront was originated by AstraZeneca. The chemical name is
(7Alpha,
17~i)-7-[9-[(4,4, 5, 5,5-pentafluoropentyl)sulfinyl] nonyl]-estra-1,3,5(10)-
triene-3,17-diol.
The chemical structure is
OH
O
S F F F
H 0 -,.,.-
F
F
Enzyme Inhibitors
The sex steroid enzyme inhibiting drugs useful in the treatment regimen of
this invention
include many compounds that are well known in the art.
These agents can be viewed as inhibitors of sex steroid biosynthesis and are
referred to
herein as sex steroid enzyme inhibitors. Such compounds are those that inhibit
biosynthesis of sex steroids from precursor steroids of adrenal and/or ovarian
origins)
preferably of both ovarian and adrenal origin. Their action is preferably
exerted in the
peripheral tissues, especially in the breast and the endometrium, and
preferably inhibits
aromatase activity. These latter compounds are aromatase inhibitors.
Inhibitors of sex steroid biosynthesis include but are not limited to (i) 3-(4-
aminophenyl)-3-
ethyl-2,6-piperidinedione which is commonly called aminoglutethimide, which is
an
inhibitor of sex steroid biosynthesis of adrenal but also of ovarian and
testicular origin and
which is available from Ciba Pharmaceutical Co., Summit N.J. under the trade
name
Cytadren, and (ii) ketoconazole, an efFective testicular but also adrenal sex
steroid
biosynthesis, which is available from Janssen Pharmaceuticals, Piscataway,
N.J., under the
trade name Nizoral. Other inhibitors include 4-hydroxyandrostenedione and FCE
34304.
Other exemplary compounds include atamestane, exemestane, anastrozole,
fadrozole,
finrozole, letrozole, vorozole, and YM511. The chemical names and structures
of these
compounds are as follows:
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Atamestane: 1- methylandrosta-1, 4-diene-3, 17-dione.
Exemestane: 6-Methylene androsta-1,4-diene-3,17-dione.
0
Anastrazole: Alpha,alpha,alpha,alpha'-tetramethyl-5-(1H-1,2,4-triazol-1-
ylmethyl)-1, 3-
benzenediacetonitrile,
~ _
_N
N
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Fadrozole: 4-(5,6,7,8-Tetrahydroimidazo[1,5-a]pyridin-5-yl)- benzonitrile,
monohydrochloride
Finrozole: 4-(3-(4-Fluorophenyl)-2-hydroxy-1-(iH-1,2,4-triazol-1-yl)-propyl)-
benzonitrile.
N--;t
N
Letrozole:4,4'-(iH-1,2,4-triazol-1-ylmethylene)bis-benzonitrile
N ~.,,~ ~N
I~ I
~N
N
~N
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Vorozole: 6-[(4-chlorophenyl)-iH-1,2,4-triazol-1-ylmethyl]-1-methyl-iH-
benzotriazole.
CI
N IN N
'N
PAN 19816: YM-511 is being developed by Yamanouchi. The chemical name is: 4-[N-
(4-
bromobenzyl)-N-(4-cyanophenyl)amino]-4H-1,2,4-triazole.
I
N,~,~.' ~'' N ,r''
I
N
r
N-N
When an inhibitor of adrenal sex steroid biosynthesis, e.g., aminoglutethimide
is
administered, cortisol biosynthesis is blocked. Accordingly, a glucocorticoid,
e.g.,
hydrocortisone, is preferably administered in physiological amounts sufficient
to maintain
normal glucocorticoid activity. Synthetic glucocorticoids, such as
dexamethasone, can also
be used.
Inhibitors of 3f3-hydroxysteroid or .DELTA.S -.DELTA.4 -isomerase activity,
such as
Trilostane, Eposlane or 4-MA, are also useful. Others, such as 16-methylene
estrone and
16-methylene estradiol, act as specific inhibitors of l7fi-estradiol
dehydrogenase (Thomas
et al., J. Biol. Chem. 258: 11500-11504, 1983).
Androgens
An androgen is a hormone that, among other activities, stimulates activity of
the accessory
male sex organs and encourages development of male sex characteristics. The
androgenic
29
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agents useful in the treatment regimen of this invention include many
compounds well
known in the art.
Typically suitable androgens include 6-alpha-methyl,l7-alpha-acetoxy
progesterone or
medroxyprogesterone acetate available, among others, from Upjohn and
Farmitalia Carlo
Erba, S.p.A. under the trade names, among others, of Provera and Farlutal, and
the
acronym MPA.
Other suitable androgens include certain compounds that can be described as
synthetic
progestins [see Labria et al. (Fertil. Steril. 31: 29-34, 1979)] and anabolic
steroids
(Raynaud and Ojasoo, Innovative Approaches in Drug Research. Elsevier Sc.
Publishers,
Amsterdam, pp. 47-72, 1986; Sandberg and Kirdoni, Pharmac. Ther. 36: 263-307,
1988;
and Vincens, Simard and De Lignieres, Les Androgenes. In: Pharmacologie
Clinique, Base
de Therapeutique, 2i eme edition, Expansion Scientifique (Paris), pp. 2139-
2158, 1988),
anabolic steroids (Lamb, Am. J. Sports Medicine 12, 31-38, 1984; Hilf, R.
Anabolic-
androgenic steroids and experimental tumors. In: (Kochachian, C. D., ed.),
Handbook of
Experimental Pharmacology, vol. 43, Anabolic-Androgenic Steroids, Springer-
Verlag, Berlin,
725 pp., 1976). Examples of anabolic steroids include Calusterone
(7[i,l7.alpha.-dimethyl-
testosterone), fluoxymesterone (9.alpha.-fluoro-iifi-hydroxy-l7.alpha.-methyl
testosterone), testosterone 17f3-cyprionate, l7.alpha.-methyltestosterone,
Pantestone
(testosterone undecanoate), .DELTA.1 -testololactone and Andractim. Some
androgens
also have progestin activity.
Progestins
A progestin is a substance that effects some or all of the changes produced by
progesterone. Typically suitable progestins include 17,21-dimethyl-19-nor-4,9-
pregnadiene-3,20-dione ("R5020, promegestone") available from Roussel-UCLAF;
cyproterone acetate (Androcur) available from Schering Ag.; 6-alpha-methyl, 17-
alpha-
acetoxy progesterone or medroxyprogesterone acetate (MPA) available from,
among
others, Upjohn and Farmitalia, Calbo Erba; Gestoden available from Shering;
magestrol
acetate (l7.alpha.-acetoxy-6-methyl-pregna-4,6-diene-3,20-dione) available
from Mead
Johnson & Co., Evansville, Ind., under the trade name of Megace. Other
progestins include
Levolorgestrel, Gestodene, desogestrel, 3-keto-desogestrel, norethindrone,
norethisterone,
l3.alpha.-ethyl-17-hydroxy-18,19-dinor-17f3-pregna-4,9,11-triene-20-yl-3-one
(R2323),
demegestone, norgestrienone, gastrinone, progesterone itself, and others
described in
CA 02424299 2003-03-28
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Raynaud and Ojasoo, J. Steroid Biochem. 25: 811-833, 1986; Raynaud et al., J.
Steroid
Biochem. 12: 143-157, 1980; Raynaud, Ojasoo and Labrie, Steroid Hormones,
Agonists
and Antagonists, In: Mechanisms of Steroid Action (G. P. Lewis and M.
Ginsburg, eds),
McMillan Press, London, pp. 145-158 (1981).
Proiactin Secretion Inhibitors
A prolactin secretion inhibitor is an agent that reduces the production of the
protein
hormone prolactin from the pituitary gland. An example is bromocriptine
available from
Novartis as Parlodel.
Growth Hormone Secretion Inhibitors
A growth hormone secretion inhibitor is an agent that reduces the secretion of
the protein
growth hormone (also called somatotropin) from the pituitary gland. Examples
include
somatostatin (available from Novartis as Sandostatin), bromocriptine, and
octreotide.
ACTH Secretion Inhibitors
An ACTH secretion inhibitor is an agent that reduces the secretion of the
peptide hormone
ACTH from the pituitary gland. An example is hydrocortisone, available as
Solucortet from
Pharmacia/Upjohn.
Reducing Ovarian Hormonal Secretions
As discussed previously, the various aspects of this invention are
particularly useful for
women in which the ovarian hormonal secretions are reduced. The invention is
particularly
valuable in postmenopausal women in whom the ovarian hormonal secretion is
naturally
reduced. Ovarian hormonal secretions also may be reduced by surgically
removing the
ovaries (oophorectomy) or chemically blocking secretion by administering an
effective
amount of an LHRH analog, which may be an LHRH agonist or antagonist. In one
aspect,
the present invention provides a method of treating breast cancer in a warm-
blooded
animal, which comprises administering (as part of a NCE regimen) to an animal
in need of
such treatment a properly selected LHRH analog, a properly selected
antiestrogen, at least
one properly selected inhibitor of sex steroid formation, and optionally a
properly selected
androgen, progestin, a glucocorticoid, or an inhibitor of prolactin secretion,
growth
hormone secretion, or ACTH secretion, in amounts sufficient to treat breast
cancer.
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While the LHRH analog may be an LHRH agonist or an LHRH antagonist, the use of
a
LHRH agonist is more preferred. Examples of LHRH analogs include leuprolide,
nafarelin,
goserelin, buserelin, and the like.
By the term "LHRH agonist" is meant synthetic analogues of the natural
luteinizing
hormone-releasing hormone (LHRH), for example, a decapeptide of the structure:
L-
pyroglutamyl-L-histidyl-L-tryptophyl-L-Beryl-L-tyrosyl-glycyl-L-leucyl-L-
arginyl-L-
propylglycyl-NH2. Suitable LHRH agonists include nonapeptides and decapeptides
represented by the formula: L-pyroglutamyl-L-histidyl-L-tryptophyl-L-seryl-L-
tyrosyl-X-Y-
arginyl-L-prolyl-Z wherein X is D-tryptophyl, D-leucyl, D-alanyl, iminobenzyl-
D-histidyl, 3-
(2-naphthyl)-D-alanyl, O-tert-butyl-D-Beryl, D-tyrosyl, D-lysyl, D-
phenylalanyl or N-methyl-
D-alanyl and Y is L-leucyl, D-leucyl, N.alpha. -methyl D-leucyl, N.alpha. -
methyl-L-leucyl or
D-alanyl and wherein Z is glycyl-NHRi or NHRi wherein Ri is H, lower alkyl or
lower
haloalkyl. Lower alkyl includes straight- or branched-chain alkyls having 1 to
6 carbon
atoms, e.g.; methyl, ethyl, propyl, pentyl or hexyl, isobutyl, neopentyl and
the like. Lower
haloalkyl includes straight- and branched-chain alkyls of 1 to 6 carbon atoms
having a
halogen substituent, e.g., --CF3, --CH2 CF3, --CF2 CH3. Halogen means F, CI,
Br, I with CI
being preferred.
In preferred nonapeptides, Y is L-leucyl, X is an optically active D-form of
tryptophan,
serine (t-Bu0), leucine, histidine (iminobenzyl), and alanine.
Preferred decapeptides include [D-Trp6 ]-LHRH wherein X-D-Trp, Y-L-leucyl, Z-
glycyl-NH2,
[D-Phe6 ]LHRH wherein X-D-phenylalanyl, Y-L-leucyl and Z-glycyl-HN3) or [D-
Nal(2)6
]LHRH which is [(3-(2-naphthyl)-D-Ala6 ]LH-RH wherein X-3-(2-naphthyl)-D-
alanyl, Y-L-
leucyl and Z-glycyl-NH3).
Other LHRH agonists useful within the scope of this invention are the .alpha.-
aza
analogues of the natural LH-RH, especially, [D-Phe6, AzgIylO ]-LHRH, [D-
Tyr(Me)6,
AzgIylO ]-LHRH, and [D-Ser-(t-Bu0)6, AzgIylO ]-LHRH, disclosed by A. S. Dutta
et al. in J.
Med. Chem., 21, 1018 (1978) and U.S. Pat. No. 4,100,274 as well as those
disclosed in
U.S. Pat. Nos. 4,024,248 and 4,118,483.
Typical suitable LHRH antagonists include [N-Ac-D-p-CI-Phel,3,D-Phe3, D-Arg6,
D-AIalO
]LHRH disclosed by J. Ercheggi et al., Biochem. Biophys. Res. Commun. 100, 915-
920,
(1981); [N-Ac-D-p-CI-Phel,2, D-Trp3, D-Arg6, D-AIalO ]LHRH disclosed by D. H.
Coy et al.,
Endocrinology, 110: 1445-1447, (1982); [N-Ac-D-(3-(2-naphthyl)-Ala)1, D-p-CI-
Phe2, D-
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Trp3, D-hArg(Et2)6, D-AIalO ]-LHRH and [N-Ac-Prol, D-p-F-Phe2, (D-(3-(2-
naphthyl)A1a3,6 ]-LHRH disclosed by J. J. Nestor et al. J. Steroid Biochem.,
20 (No. 6B),
1366 (1984); the nona- and decapeptides analogs of LHRH useful as LHRH
antagonists
disclosed in U.S. Pat. No. 4,481,190 (J. J. Nestor et al.); analogs of the
highly constrained
cyclic antagonist, cycle [.DELTA.3 Prol, D-p-CI-Phe2, D-Trp3,5, N-Me-Leu7, f3-
AIalO ]LHRH
disclosed by J. Rivier, J. Steroid Biochem., 20, (No. 6B), 1365 (1984), and [N-
Ac-D-(3-(2-
naphthyl)-Alal, D-p-F-Phe2, D-Trp3, D-Arg6 ]-LHRH disclosed by A. Corbin et
al., J. Steroid
Biochem. 20 (No. 6B) 1369 (1984).
Other LHRH agonist and antagonist analogs are disclosed in LHRH and its
Analogues (B. H.
Vickery et al. editors at page 3-10 (J. J. Nestor), 11-22 (J. Rivier et al.)
and 23-33 (J. J.
Nestor et al.).
The LHRH agonists and antagonists useful in this invention may conveniently be
prepared
by the method described by Stewart et al. in "Solid Phase Peptide Synthesis"
(published in
1969 by Freeman & Co., San Francisco, page 1) but solution synthesis may also
be used.
The nona- and decapeptides used in this invention are conveniently assembled
on a solid
resin support, such as 1% cross-linked Pro-Merrifield resin by use of an
automatic peptide
synthesizer. Typically, side-chain protecting groups, well known to those in
the peptide
arts, are used during the dicyclohexylcarbodiimide-catalyzed coupling of a
tert-
butyoxycarbonylamino acid to the growing peptide attached to a benzhydrylamine
resin.
The tert-butyloxycarbonyl protecting groups are removed at each stage with
trifluoracetic
acid. The nona- or decapeptide is cleaved from the resin and deprotected by
use of HF.
The crude peptide is purified by the usual techniques, e.g., gel filtration,
HPLC and
partition chromatography and optionally lyophilization. See also D. H. Coy et
al., J. Med.
Chem. 19, pages 423-452, (1976).
To reduce the ovarian hormonal secretions, a properly selected LHRH agonist is
administered parenterally (e.g., subcutaneously, intranasally,
intramuscularly) and a
properly selected androgen, a properly selected antiestrogen, and at least one
properly
selected inhibitor of sex steroid formation are each administered orally.
In addition to the process for identifying a combination treatment and the
method for
treating breast cancer, other aspects of the invention relate to preventive
aspects using
the same ADME evaluation. Thus one aspect is a process for identifying a
combination of
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drugs for prevention of breast cancer in an animal predisposed to such cancer.
The
process comprises
identifying antiestrogen drugs and a therapeutically-effective dosage range
for an antiestrogen so identified,
determining the absorption, distribution, metabolism, and excretion
characteristics for the antiestrogen,
identifying sex steroid enzyme inhibitor drugs and therapeutically-effective
dosage ranges for an enzyme inhibitor so identified,
determining the absorption, distribution, metabolism, and excretion
characteristics of an enzyme inhibitor so identified,
choosing each drug and a dosage range for each drug such that each drug
exhibits useful therapeutic activity but each drug exhibits minimal
interference with the
absorption, distribution, metabolism, and excretion of the other drug.
Another aspect is a method of preventing breast cancer in an animal
predisposed to such
cancer. The process comprises
administering to the animal a therapeutically-effective amount of an
antiestrogen drug and
concurrently administering a therapeutically-effective amount of a sex
steroid enzyme inhibitor drug, wherein the antiestrogen and the enzyme
inhibitor, and
dosages for each, are chosen so that there is minimal material interference by
one drug on
the absorption, distribution, metabolism, and excretion of the other drug.
Still other aspects of the invention relate to a processes for optimizing
treatment of a
breast cancer patient or for optimizing a cancer-preventive regimen in an
animal
predisposed to such cancer. In either case, the process comprises
identifying antiestrogens and a therapeutically-effective dosage range for an
antiestrogen so identified,
determining the absorption, distribution, metabolism, and excretion
characteristics for the antiestrogen in the patient;
identifying sex steroid enzyme inhibitors and a therapeutically-effective
dosage range for an enzyme inhibitor so identified;
determining the absorption, distribution, metabolism, and excretion
characteristics for an enzyme inhibitor so identified;
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selecting the antiestrogen and an enzyme inhibitor, and a dosage range for
each, so that material interference is minimized with respect to the
absorption, distribution,
metabolism, and excretion characteristics of one towards the other; and
co-administering the selected antiestrogen and the enzyme inhibitor to the
patient at the dosages selected.
The other agents discussed herein before (i.e. an androgen, a progestin, a
glucocorticoid, or an inhibitor of prolactin, ACTH, or growth hormone section)
can be
employed as discussed previously.
One further aspect of this invention relates to a kit that is useful in the
method of
treating or preventing breast cancer. The kit comprises an antiestrogen drug
in a dosage
form to provide a therapeutically-effective amount of the antiestrogen and a
therapeutically-effective amount of a sex steroid enzyme inhibitor drug,
wherein the
dosage form and amount of each drug are chosen so that there is minimal
material
interference with respect to absorption, distribution, metabolism, and
excretion
characteristics of one drug towards the other drug. The kit may also include
labeling
instructions for the use of the combination to treat breast cancer in a
patient or to prevent
breast cancer in a patient that is predisposed to such cancer in accordance
with the
method of this invention. Other agents, as discussed hereinbefore, may be
included in the
kit in a dosage form and in an amount that do not interfere with the ADME
characteristics
among the active agents present.
A further aspect of this invention is a pharmaceutical composition for
treating or
preventing breast cancer that comprises a therapeutically-effective amount of
an
antiestrogen drug and a therapeutically-effective amount of a sex steroid
enzyme inhibitor
drug, wherein the amount of each drug is chosen so that there is minimal
material
interference between one drug's absorption, distribution, metabolism, and
excretion
characteristics and the other agent's absorption, distribution, metabolism,
and excretion
characteristics in a patient.
Thus, this invention provides a mechanism that leads to the effective
treatment of breast
cancer using an NCE regimen and provides teaching that is distinctly different
than that
from prior art wherein superficially similar combinations of drug classes can
and have, in
fact, led to suboptimal efficacy or excessive side effects.
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By combining an optimal blockade of estrogen formation and/or action and the
inhibitory
effect of other agents on breast and endometrial cancer cell growth, the
present invention
provides a method of maximally inhibiting the growth of breast and endometrial
cancer.
To assist in determining the effect of the treatment, plasma concentrations of
the sex
steroids of adrenal and ovarian origin, i.e., precursor steroids, androgens
and estrogens,
and tumor size may be measured. However, the proper selection of an NCE
regimen, with
predictably better outcomes, may be of more utility than use of the surrogate
marker of
plasma levels of estrogens. Lowered concentrations of sex steroids and
reduction in tumor
size may be indicative of successful treatment, e.g., inhibition of tumor
growth using active
compounds described herein in accordance with the present invention, although
relatively
raised levels could be expected if non-NCE regimens are employed. The
concentrations of
adrenal androgens and estrogens such as dehydroepiandrosterone (DHEA), DHEA-S
sulfate
(DHEAS), androst-5-ene-3B,17f3-diol (.DELTA.'-diol) and, the ovarian estrogen,
17f3-
estradiol (E2) are measured by standard methods well known to those skilled in
the art,
see for example, F. Labrie et al., The Prostate 4, 579-584, 1983; Luthy et
al., J. Gynecol.
Endocrinol., 1, 151-158, 1987).
The change in tumor size is measured by standard physical methods well known
to those
skilled in the art, e.g., bone scan, chest X-ray, skeletal survey,
ultrasonography, nuclear
medicine scans, computerized tomography, magnetic resonance imaging, positron
emission tomography, physical examination, and the like.
The following example provides a representative combination that is useful in
the method,
process, kit, and composition aspects of the invention.
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Example I
Application of the process to atamestane and toremifene*
An example of the application of the method is shown in the table. The
chemical
structures, pharmacokinetic profiles, and the patterns of the absorption,
distribution,
metabolism, and excretion have little or no overlap in the categories an
related
subcategories. This lack of overlap suggests little or no possible adverse
drug-drug
interaction and, therefore, that atamestane and toremifene are an example of
an NCE
regimen.
Atamestane Toremifene
Factors to be considered in
the application of the process
Chemical structure (See "Detailedsteroid non-steroid
Description's
Pharmacokinetic profile
tmax (time) 1 hour 3 hours
distribution ti~z (time) < 1 hour 4 hours
elimination tl~z (time) < 24 hours 5 days
total clearance (volume/unit 84 liters/hour 5 liters/hour
time)
overall time to steady state hours 4-6 weeks
Absorption
route oral oral
influenced by food high fat diet no
increases plasma
levels
Distribution
plasma protein binding (%) 80 - 90 > 99.5
principal plasma binding proteins)a-1 acid glycoprotein;albumin
steroid binding
globulin(s);
albumin
Excretion
primary route of elimination renal fecal
enterohepatic circulation no yes
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Atamestane Toremifene
Metabolism
primary enzyme(s)* 5~3 reductase; CYP3A4
17(3 hydroxysteroid-
dehyrogenase;
mixed
function oxidase
induction of primary metabolizingno no
enzyme
plasma levels affected by knownno yes
inducers of (no change in (2-fold increase
cytochrome p-450 enzyme systempharmacokinetics)in
clearance and
decrease in
half-life)
primary metabolite active yes yes
significant pre-systemic metabolismyes no
Endocrine effect
primary mechanism enzyme inhibitionreceptor blockade
feedback stimulation on combinationno yes
drug's
primary mechanism
direct inhibition of primary no no
mechanism by
combination drug
estrogen receptor binding withno yes
residual
estrogenic effect
Other Effects on ADME or PK
age of patient no yes: increases
in
elimination
tl,z and
volume of distribution
with increasing
age
sex of patient no no known effect
race of patient unknown unexpected
decreases in renal function unexpected not applicable
decreases in hepatic function unexpected yes: increases
in
elimination
tl~Z and
decreasing function
* Using standard methodology (adapted from Tucker et al., 2001, "Optimizing
Drug
Development: Strategies to Assess Drug Metabolism/Transporter Interaction
Potential
Pharmaceutical Research," Pharmaceutical Research 18: 1071-80; see also Tucker
et al.,
2001, "Optimizing Drug Development: Strategies to assess
Metabolism/Transporter
Interaction Potential--Towards a Consensus," Br. J. Clin. Pharmacol. 52(1):107-
117; Tucker
et al., 2001, "EUFEPS Conference Report. Optimizing Drug Development:
Strategies to
assess Metabolism/Transporter Interaction Potential--Towards a Consensus,"
Eur. J.
Pharm. Sci. 13(4):417-428; Tucker et al., 2001, "Optimizing Drug Development:
Strategies
to assess Metabolism/Transporter Interaction Potential--Towards a Consensus,"
Clin.
Pharmacol. Ther. 70(2):103-114), we have demonstrated that the combination of
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atamestane and toremifene (0.1 and 5.0 pg/mL, respectively) does not
substantially inhibit
CYP isoenzymes 1A2, 3A4, 2C19, 2D6 or 2E1.
By reviewing the ADME characteristics in the above table one can see that
there is minimal
material interference between atamestane (an aromatase inhibitor) and
toremifene (an
antiestrogen). With regard to absorption, both drugs are orally absorbed and
only
atamestane is influenced by food, i.e. plasma levels are increased by a high
fat diet.
Regarding distribution, both bind to plasma protein, but each binds to a
different protein.
Each drug is primarily excreted by a different route, and while toremifene is
subject to
enterohepatic circulation, atamestane is not. Each drug's primary enzymatic
metabolism
differs as shown and the other factors establish that there should be little
if any
interference. With regard to the endocrine effect, the primary mechanism for
atamestane
is enzyme inhibition, while that of toremifene is receptor blockade.
A useful regimen for this combination is to administer toremifene once a day
orally at a
standard dose and administer 500 mg of atamestane daily, preferably 300 mg in
the
morning and 200 mg in the evening about 12 hours later.
One skilled in the art will also recognize that a properly chosen NCE regimen
will also be
useful in the treatment or prevention of other types of cancer such as
endometrial cancer.
One skilled in the art will also recognize that one or more aspects of this
invention must be
used to optimally treat or prevent a disorder (particularly metastatic breast
cancer in
postmenopausal women) using a rational combination of appropriate drugs.
The terms and descriptions used herein are preferred embodiments set forth by
way of
illustration only and are not intended as limitations on the many variations
which those of
skill in the art will recognize to be possible in practicing the present
invention as defined by
the following claims.
39
